About M-Series Connectors

There are multiple sizes of connectors which
practitioners tend to call "Microdot". The most common size
uses
10-32
threads, but there are also
5-44
and
1/4-32
variants, as shown in this image.

This style of connector was pioneered by Malco in
the late 1950's and early 1960's. Malco was later
bought by Microdot, which was later bought by Tyco.
Because of this history, users in the
industries that use this connector style still
call this a "Microdot connector", or even "Malco
Connector", even though there are now multiple
manufacturers making compatible connectors.
"Microdot" is a trademark of Tyco.

The connectors we provide are compatibles made by
various manufacturers. They are often improved
designs, mechanically more durable than the original
Malco connector.

1/4-32 (M25) Connector Details

These connectors have threads that are the same as
those on a 1/4-32 (UNF) machine screw, and are
compatible with Microdot brand S-93 connectors. S-93
connectors are commonly used on nuclear particle detectors,
such as those made by
ORTEC.

These connectors are often confused with
10-32
connectors; they look similar, varying only slightly
in size.
If in doubt,
check your mating connector using a thread gauge or
caliper: 1/4-32 threads have a
minor diameter
of approximately 5.4 mm, while 10-32
threads have a minor diameter of about 3.9 mm. See a
thread chart
for more details.

About Low Loss Cable

This is Belden's 7805 "low loss" cable. It's similar to RG174, but
with a solid copper core and a layer of foil added under the braid.
This combination causes less attenuation, providing roughly 50% more
signal as measured in decibels. 7805 also works better at higher
frequencies, and is rated up to 6 GHz. The foil layer also provides
for better EMF shielding versus braid alone.

We see this cable used in fixed-place permanent installations such as
wifi and GPS antenna extensions, other RF applications, low-voltage
signal sources including radiation detectors and strain gauges,
high-frequency or fast-rise transient signals, and other low-vibration
applications in aerospace, nuclear physics, petroleum refining and
chemical processing.

This cable is not recommended for use in applications where it
will undergo repeated cycles of flexing or vibration -- the solid core
will eventually break under those conditions. You may instead want
one of these stranded-core RG174 variants:

RG174 TPR has a
stranded core and TPR jacket. The TPR jacket provides for more
flexibility, most useful in bench and handheld applications.

RG174 low
noise has a stranded core, PVC jacket, and a carbon layer
under the braid. The carbon layer reduces flexing-induced static
and provides some additional shielding. It's best at lower
frequencies -- see the notes on that page.

RG174 low loss Specifications

The following are nominal values; if you have exact requirements that
need to be met for a given application, please contact us.

Impedance

50 ohms

Capacitance

102.3 pF/meter (31.2 pF/foot)

Minimum Operating Temperature

-40 C (-40.0 F)

Maximum Operating Temperature

80 C (176.0 F)

Jacket Diameter

2.8 mm

Jacket Material

PVC

Velocity Ratio

66%

Core

solid

Related

Belden 7805

We hi-pot test our cable assemblies for high-voltage breakdown
between core and braid. See About Hi-Pot
Testing for why this might matter to you, particularly for
physics or NDT applications. Caution: We make no claims as to the
safety of this product for high-voltage use. These voltages can
kill. Do not handle or approach any cable or conductor carrying
high voltage; this includes insulated cables, nearby metal parts,
water, and other conductive materials. Engineering and design for
safety in your application are your responsibility.

Customization and Ordering

We make our own cable assemblies. If you need a connector
type that you don't see here, or if you have custom requirements,
feel free to contact us.